Implant with a through passage

ABSTRACT

Implant with through passage (11) and intended to be applied as a through passage in the skin or in a membrane of the human body. The implant comprises a tubular body (10) provided with a radially protruding circular protruding flange (12), the perforation of flange (12) as least closest to the tubular body comprising slots (15) extending in the peripherical direction of the flange.

The present invention refers to an implant with a through passage and isintended to be applied as a passage through the skin or a membrane ofthe human body, the implant comprising a tubular body provided with aradially protruding circular perforated flange.

Implants of this type are disclosed e.g. in DE-A-26 45 990, U.S. Pat.Nos. 4,217,664, 3,663,965, EP-A1-0 367 357 and WO 87/06122. In all thosecases, the flange is intended to be disposed under the skin. Accordingto for example EP-A1-0 367 357 and WO 87/06122 the flange is disposed inthe connective tissue under the skin in order to permit the growth ofconnective tissue through the perforation of the flange for anchoring ofthe implant. For the purpose of preventing downward epithelial growtharound the implant and thus preventing the rejection of the implant thetubular body is arranged, according to WO 87/06122, with grooves whichare delimited between perforated flanges in order to permit the growthof connective tissue into these grooves and thus preventing the downwardgrowth of the epithelial layer along the tubular body.

The object of the invention is to bring about an implant of the abovementioned type, which combines great bearing capacity, i.e. largebearing surface of the flange, with good stability, i.e. good retentionof the flange due to growth of the surrounding connective tissue intosaid flange, the downward epithelial growth at the same time beingprevented by the growth of connective tissue into the flange. Theimplant according to the invention is adapted to be used as a passagethrough the skin in order to be accessible from the outside to theinterior of the organism through the passage in the tubular body, but itmay also advantageously be used as a passage in a membrane, for examplethe peritoneum, the intestinal wall or other membranes of body cavitiesin the organism.

In order to further explain the invention reference is made to theaccompanying drawing, in which

FIG. 1 is a side view and a sectional view which shows the use of theimplant according to the invention partly as a passage through the skinand partly as a passage through e.g. an intestinal mucous membrane inorder to achieve a connection from the outside to the interior of theintestine,

FIG. 2 is a plan view of the flange on the implant,

FIG. 3 is an axial sectional view of a practical embodiment according tothe invention arranged as a passage through the skin, the left half ofthe figure showing the implant with bone support and the right halfshowing the implant with soft-tissue support, and

FIG. 4 is a plan view of the implant in FIG. 3.

The implant should be made of a biocompatible material, for exampletitanium or a suitable plastic. It comprises, according to FIGS. 1 and2, a body 10 having a through channel 11. One end the body forms acircular or disc-shaped flange 12 whereas the other end forms anenlarged ball-shaped or bulbous portion 13 which can be more or lessspherical but also may be mushroom-shaped. This portion connects to theflange at a circular neck 14 with a concavely rounded surface.

The flange is perforated and the perforation consists of slots 15 whichextend concentrically in the circumferential direction of the flange andwhich overlap each other or are arranged one upon the other as shown inFIG. 2. As few bridges 12' as possible should be arranged between theslots in every ring of slots; at least three bridges should be provided,however, for strength reasons.

In FIG. 1 two identical implants are connected with each other by acatheter 16, one implant forming a passage in the skin 17 while theother implant forms a passage in for example an intestinal wall 18 withan intestinal mucous membrane 18', the implant with the catheter inbetween forming a permanent connection from the outside to the interiorof the intestine for sampling the contents of the intestine or forsupplying medicine or the like to the intestine. That implant whichforms the passage through the skin has its flange 12 located in theconnective tissue under the skin in order to allow growth of connectivetissue through the perforation into the flange for anchoring theimplant. By this inward growth, however, and above all in the areaadjacent to the body 10, an effective barrier against downward growth ofthe epithelial layer of the skin is obtained without the need ofproviding special means for this purpose. Rejection of the implant couldbe caused by the downward growth of the epithelial layer. In order tomake the flange fulfil the mentioned twotold function of forming ananchorage means and preventing epithelial downward growth, the length ofthe neck, on the basis of what has been found, should not be greaterthan 5 mm, preferably 3 mm. Due to this, the slots 15 closest to thebody 10 are disposed at a distance of 3-5 mm from the surface of theskin or the intestinal mucous membrane, respectively, which means that abarrier of connective tissue will have the time needed to establishitself by inward growth of the connective tissue through the flangebefore the epithelial layer or the intestinal mucous membrane,respectively, has managed to grow down to the slots located closest tothe body 10. The ball-shaped portion should be as low as possible inorder not to disturb adjacent organs. It is suitably bright polished inorder to exhibit the lowest possible surface tension, whereby the mucousmembrane or the skin is prevented from growing over the implant.

The implant in the intestinal wall 18 is arranged with its flangeagainst the outside of the intestinal wall. It can initially be retainedin the intestinal wall by punching a hole in the intestinal wall 18,which has a smaller diameter than the ball-shaped portion 13 and then bypressing the portion through the intestinal wall while elasticallyenlarging the hole. By the inward growth of surrounding soft tissue intothe flange the implant in the intestinal wall will be securely anchoredto said wall. By bright polishing the ball-shaped portion 13 overgrowthof this portion is prevented, which is extremely important since theimplant is not accessible from the outside for removal of possibleovergrowth on the inside of the intestinal wall. The ball-shaped portion13 has to be as low as possible here in order not to form an obstructionin the abdominal cavity etc. However, it has to rise at least 1 mm abovethe mucous membrane 18', preferably somewhat more.

In the practical embodiment of the implant according to the invention,which is shown in FIGS. 3 and 4, the implant is arranged as a passagethrough the skin in the left half of FIG. 3 with bone support and in theright half of FIG. 3 with soft-tissue support. The body 10 is here madecylindrical. When the implant has bone support according to the lefthalf of FIG. 3, the circular flange 12 is made very thin and itsthickness should lie between 0.05 and 3 mm, preferably about 0.2 mm. Theflange may be disposed either on the top of the periosteum 20 of thebone 19 or inserted between the bone and the periosteum. In the righthalf of FIG. 3 the flange lies solely in the connective tissue 17'. Inthis case the flange is made very thin in the area of the slots 15,i.e., as thin as the flange in the left half of the figure, while theflange, radially outward of the slots may be thicker and may graduallyincrease to greater thickness. In this part of the flange through holes21 are arranged instead of slots. By making the flange very thin in thearea of the slots closest to the body 10 the connective tissue 17'surrounding the flange can grow as fast as possible through the slotsinto the flange for healing up the implant due to the fact that theconnective tissue on top of the flange through the slots immediatelymeets and by growth joins the connective tissue under the flange. Alledges of holes and slots and of the periphery of the flange should besoftly rounded in order not to have a cutting effect and thus causingirritation in the tissue.

In a suitable embodiment of the invention the distance between the body10 and the closest located slots should be 3-5 mm, the slots having awidth of about 1 mm and the distance between them also being about 1 mm.The bridges 12' between the slots in one and the same ring of slots issuitably about 1 mm and, for strength reasons there should be at leastthree such bridges in each ring. The width of the slots and the distancebetween the slots, respectively, should be greater than 30 μm andsuitably within the range of 0.1-2 mm. The thickness of the material inthe thinner part of the flange should be between 0.05-3 mm and issuitably about 0.2 mm. The holes 21 radially outwardly of the slots havesuitably a diameter of about 2 mm and the outermost portion of theflange, that portion which lies between the periphery of the flange andthe outermost row of holes 21, should have a thickness and a widthbetween 1-3 mm. It is especially important that this portion is softlyrounded for the reasons mentioned above. The flange 12 may have adiameter which lies between 6-36 mm whereas the diameter of the body 10lies between 1-16 mm.

Of course, the connective tissue will grow through the flange not onlyinto the slots where it is important to have a rapid inward growth inthe area closest to the body 10 in order to prevent downward growth ofthe epithelial layer 17 and the intestinal mucous membrane 18',respectively, but the connective tissue will, of course, also growthrough the holes 21, though somewhat slower. The number of holes andthe diameter thereof should be chosen in such a way that a balancebetween the bearing capacity of the flange, which means that the flangeshall have a large bearing surface (the nonperforated part of theflange), and the stability of the flange, which is dependent on thatretention of the implant which is attained by the inward growth of theconnective tissue into the holes 21.

In FIG. 3 a transverse dashed line 22 is drawn on the body 22, whichindicates a parting line. By manufacturing the upper portion of the body10 as a separate part which may be detachably attached to the remainingpart of the body, a two-step method can be applied when inserting theimplant by surgery according to FIG. 3. With the detachable part of thebody 10 removed, the implant is inserted by surgery and the skin or themucous membrane, respectively, is allowed to grow over the implant.After this first step and after healing during inward growth ofconnective tissue into the slots, a perforation of the skin or themucous membrane, respectively, is accomplished in a second step and theseparate upper portion of the body 10 is applied on the already ingrownpart of the implant and is allowed to protrude through the perforation.The epithelial layer of the skin of the mesothelial layer of the mucousmembrane, respectively, is now effectively prevented from growingdownwards along the body 10 during the continous inward growth ofconnective tissue into the holes 21 into the flange, since the necessaryinward growth of connective tissue into the slots around the body hasalready taken place in order to prevent downward epithelial growth. Thesame method can be applied when inserting the implant by surgery forexample in the abdominal or intestinal wall.

In order to further render the preventing function of downwardepithelial growth by the connective tissue more effective, the totalarea of the flange (including both the upper side and under side, butabove all the slotted area and the area between the slotted area and thetubular body) should be designed with a topography consisting ofgrooves, holes etc. having a width or a diameter of 1-8 μm, preferably2-4 μm, and with a relative distance of likewise 1-8 μm, preferably 2-4μm. This is suitably achieved by a known so called litographictechnique. By this surface topographical arrangement the fibroblasts ofthe connective tissue will exceptionally intimately adhere to thesurface of the flange thereby further preventing the epithelial downwardgrowth.

I claim:
 1. An implant, comprising:a first part of bulbousconfiguration; a second part of flat, disc-shaped configuration; a neckinterconnecting said first and second parts, said neck having a diameterless than respective diameters of said first and second parts; a centralthroughbore formed in said first part, said neck, and said second part;and a plurality of sets of concentric, radially equidistantly spacedapart slots formed in said second part; each of said slots having apredetermined circumferential extent, there being a plurality ofcircumferentially spaced apart slots formed in each set of slots.
 2. Theimplant of claim 1, wherein the slots in each set of slots are staggeredas between radially contiguous sets of slots so that a preselectedimaginary radially extending straight line emanating from said centralthroughbore alternately passes through slots and unslotted parts of saidsecond part.
 3. The implant of claims 1 or 2, wherein said second parthas a thickness between 0.05 and 3.0 mm.
 4. The implant of claims 1 or2, wherein said slots have a radial width between 0.1 and 2.0 mm.
 5. Theimplant of claims 1 or 2, wherein radially contiguous slots are spacedapart by a radial distance between 0.1 and 2.0 mm.
 6. The implant ofclaims 1 or 2, wherein each of said slots have rounded edges and whereinsaid second part has a rounded peripheral edge.
 7. The implant of claims1 or 2, wherein said neck has a length of about 3 mm.
 8. An implant,comprising:a first part of bulbous configuration; a second part of flat,disc-shaped configuration; a neck interconnecting said first and secondparts, said neck having a diameter less than respective diameters ofsaid first and second parts; a central throughbore formed in said firstpart, said neck, and said second part; and a plurality of sets ofconcentric, radially equidistantly spaced apart slots formed in saidsecond part; each of said slots having a predetermined circumferentialextent, there being a plurality of circumferentially spaced apart slotsformed in each set of slots; and a plurality of sets of concentric,radially spaced apart holes formed in said second part, radiallyoutwardly of said slots
 9. The implant of claim 8, wherein the slots ineach set of slots are staggered as between radially contiguous sets ofslots so that a preselected imaginary radially extending straight lineemanating from said central throughbore alternately passes through slotsand unslotted parts of said second part.
 10. The implant of claim 9,wherein the holes in each set of holes are staggered as between radiallycontiguous sets of holes so that a preselected imaginary radiallyextending straight line emanating from said central throughborealternately passes through holes and imperforate parts of said secondpart.
 11. The implant of claim 8, wherein said slots, said holes, and aperipheral edge of said second part have rounded edges.
 12. An implant,comprising:a first part of tubular configuration; said first part havingan upper end and a lower end; a second part of flat, disc-shapedconfiguration; said second part being formed integrally with said lowerend of said first part; a central throughbore formed in said first partand said second part; a plurality of sets of concentric, radiallyequidistantly spaced apart slots formed in said second part; each ofsaid slots having a predetermined circumferential extent, there being aplurality of circumferentially spaced apart slots formed in each set ofslots; said first part including an upper, detachable part.